Previous experiments have studied discrete motor functions in rats with cortical lesions or pyramidal tract section. The proposed experiments are designed to localize the cortical areas of motor control in rats and to describe their specific anatomical projections. Rats will undergo bilateral ablations of either motor or sensory cortex followed by testing for digital functions. Another group will receive unilateral motor or sensory cortical lesions with subsequent analysis for differential cortical projections. Developmental studies are designed to examine the functional compensatory capacities of newborn animals with brain damage and to investigate the anatomical basis for recovery. Neonatal animals will receive unilateral frontal cortical ablations and at maturity to be tested for discrete motor functions. Additionally, the remaining corticospinal and rubrospinal tracts will be examined for structural reorganization such as axonal sprouting or abnormal axonal projections. This experimental paradigm provides a plausible model for correlating behavioral and anatomical plasticity.